1. Field of the Invention
This invention relates to a method for inspecting a magnetic disk cartridge composed of a cartridge and a magnetic disk housed in the cartridge, which magnetic disk is constituted of a center hub and a magnetic disk body adhered onto the center hub with an adhesive agent. This invention particularly relates to a method for inspecting a magnetic disk cartridge, wherein a judgment is made as to whether the state, with which an adhesive agent has onto a flange of a center hub for constituting a magnetic disk cartridge, is good or bad.
2. Description of the Prior Art
With rapid advances made in office automation apparatuses, or the like, and in magnetic disks serving as recording media, 3.5-inch type of or other types of magnetic disk cartridges are currently used most popularly. The magnetic disk cartridge is composed of a flexible, doughnut-shaped magnetic disk body, a hat-shaped center hub adhered to a center part of the magnetic disk body, and a hard case for housing the magnetic disk body and the center hub therein.
The accuracy, with which signals are recorded and reproduced with a magnetic disk cartridge, largely depends on whether the adhesive agent has been or has not been applied uniformly and as an annular layer onto the flange of the center hub and whether the center hub and the magnetic disk body have been accurately adhered to each other with the adhesive agent. Therefore, during the processes for manufacturing a magnetic disk cartridge, it is necessary for an inspection to be made as to whether the state, with which the adhesive agent has been applied onto the flange of the center hub for constituting the magnetic disk cartridge, is good or bad.
A technique for inspecting the state, with which an adhesive agent has been applied onto a flange of a center hub for constituting a magnetic disk cartridge, has been disclosed in, for example, Japanese Unexamined Patent Publication No. 63(1988)-205867. With the disclosed technique, a light beam (including ultraviolet light) is irradiated to a layer of an adhesive agent, which has been applied onto a flange of a center hub for constituting a magnetic disk cartridge. A light beam receiving device is located at a position that is capable of receiving the light beam, which has been reflected from the layer of the adhesive agent. The center hub is mechanically moved with respect to the light beam receiving device. In this manner, optical information representing the state, with which the adhesive agent has been applied onto the flange of the center hub for constituting a magnetic disk cartridge, is detected photoelectrically, and an electric signal representing the optical information is thereby obtained. From the level of the electric signal, a judgment is made as to whether the state, with which the adhesive agent has been applied onto the flange of the center hub for constituting a magnetic disk cartridge, is good or bad.
A different technique for inspecting the state, with which an adhesive agent has been applied onto a flange of a center hub for constituting a magnetic disk cartridge, has been disclosed in, for example, Japanese Unexamined Patent Publication No. 1(1989)-212635. With the disclosed technique, a light beam is irradiated to the whole surface of a layer of an adhesive agent, which has been applied onto a flange of a center hub for constituting a magnetic disk cartridge, and to the regions inward and outward from the layer of the adhesive agent. The light beam, which has been reflected from the whole surface of the layer of the adhesive agent and the regions inward and outward from the layer of the adhesive agent, is photoelectrically detected, and an electric signal is thereby obtained. Thereafter, operation processing is carried out on the electric signal, and a connectivity analysis is carried out. In cases where the connective components are three, it is judged that the state, with which the adhesive agent has been applied onto the flange of the center hub for constituting a magnetic disk cartridge, is good. In cases where the connective components are not three, it is judged that the state, with which the adhesive agent has been applied onto the flange of the center hub for constituting a magnetic disk cartridge, is bad.
With the conventional techniques described above, a judgment can be made only as to whether the state, with which the adhesive agent has been applied onto the flange of the center hub for constituting a magnetic disk cartridge, is good or bad, such as the presence or absence of a break in the layer of the adhesive agent, the presence or absence of protrusions of the adhesive agent from the normal position, to which the adhesive agent is to be applied, or the presence or absence of air bubbles in the layer of the adhesive agent. However, with the conventional techniques described above, inspections cannot be made as to how thick the layer of the adhesive agent is, i.e. how much the adhesive agent has been applied onto the flange of the center hub for constituting a magnetic disk cartridge.